A national survey of middle-school students asks which subject is most challenging. Which of these samples is a representative s
ample? A. 372 sixth-graders in a certain town B. 972 seventh-graders in a certain county C. 619 eighth-graders in different states D. 400 students from various states, representing different grades, 6–8
The expression of 25t +45m shows the total number of miles driven at both speeds. In order to solve this equation you would need to know the total number of hours driven in order to multiply that by the appropriate speed in terms of miles per hour.
